4-0-benzyl-3,6-dideoxy-6-fluoro preparation

Benzyl 2-acetamido-6-0-benzyl-2,4-dideoxy-4-fluoro-a-D-glucopyrano-side and the corresponding free sugar were prepared from benzyl 2-acet-amido-3-0-allyl-6-0-benzyl- (or -3,6-di-0-benzyl)-2-deoxy-a-D-galacto-pyranoside by treatment with DAST (in diglyme). 

Preparation of methyl 2,3-di-0-benzyl-l,4-dideoxy-la/ip-fluoro-D glucoheptopyranuronate ... 

Ammonolysis of l,6 3,4-dianhydro-2-0-benzyl-/3-D-galactopyran-ose (188) affords the 4-amino-4-deoxy derivative.740 It was also used for the preparation of the 2-amino-4-fluoro- and 4-amino-2-fluoro-2,4-dideoxy derivatives of l,6-anhydro-/3-D-glucopyranose.381 The oxirane ring of most dianhydrides is readily split not only by ammonia but also by its derivatives, such as methylamine, dimethylamine,320,7 7 and benzylamine.635... 

Selective acid>catalysed methanolysis of 2,3,2, 3 -tetra-0-benzyl-4,6 4, 6 -di-0-benzylidene-a,a-trehalose gave the monoacetal which was converted into the dimesylate and from this 6-deoxy-6-fluoro-a,a-trehalose was obtained. In the course of the work 4-chloro-4,6-dideoxy-6-fluoro-a-D-galactopyranosyl a-D-glucopyranoside was produced (as a derivative), and 6-iodo, 6,6 -di-iodo, 6-azido-, and 6,6 -diazido-trehalose compounds were also prepared. 6-Deoxy-6-fluoro- and 6-deoxy-6-iodo-trehalose were also obtained by way of the... 

A number of 2,6-dideoxy-6,6,6-trifluorohexoses were prepared from a six-carbon acetylenic precursor via selective hydroxylation of the derived alkene diastereomers, and differences in stereoselectivity of reduction of a trifluoro-methyl ketone compared with the corresponding methyl ketone are outlined in Chapter 18. Oxidation of methyl 5-0-benzyl-3(2)-deoxy-3(2)-fluoro-a-D-pento-furanosides (DMSO/TFAA) was accompanied by epimerization at the fluori-nated carbon atom a- to the ketone resulting in formation of the corresponding 2-(or 3-) keto derivatives as mixtures of two epimers. Reduction then afforded various mixtures of 2- and 3- fluoro compounds. ... 

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